Won't matter. We'll see it, anyway.
That may be part of the problem (though probably not the biggest part). It may be a gross oversimplification, but maybe Paramount knows they've got a built in audience that will watch the movies no matter how shitty the last one was and the new one looks. Plus, they're going for the most mainstream (and lucrative) audience possible, which generally means a lowest-common-denominator approach.
No, what needs to happen is this: the instant Battlestar Galactica has run its course, Ron Moore & company need to work their magic on the Trek universe. Sweep away everything that has gone before and reboot the whole thing. And get Katee Sackhoff to play the captain of whichever version of the Enterprise they go with.
You make a vexing point; as a fan, I keep going back because even though they made Star Trek V, they also made First Contact. (Your opinion is welcome to vary, but I loathed the former and loved the latter.) They also made ST:TNG season 2, yet recovered to make DS9 seasons 5&6.
And, keeping in mind that all things are relative, Star Wars Ep III was a drastic improvement over Ep I (though I would have re-edited the order of the scenes in the third act so that the characters actually had motivation for their actions). We go because they created a universe we fell in love with at some point, and they occasionally still give us something worth seeing in that universe.
It's kind of like the phenomenon of the familiar in restaurant franchising; we claim to hate McDonald's food (in our house, at least), but when we're out on the highway, and desperate for a place to eat, we'll choose the familiar arches over "Joe's Armpit BBQ" most of the time. Joe's may be better, but if we don't know that, we won't necessarily take the risk; studios and publishers know this, which is why there are so many franchises out there.
Gawd, economic realities are depressing.
I reiterate: this is why I'm rooting for the Escape Pod format to take off.